linux-kernel - Re: [PATCH] console keyboard mapping broken by 04c71976

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Message-ID: <20080611151028.GB11462@midget.suse.cz>
Date:	Wed, 11 Jun 2008 17:10:28 +0200
From:	Jiri Bohac <jbohac@...e.cz>
To:	Samuel Thibault <samuel.thibault@...-lyon.org>,
	Jiri Bohac <jbohac@...e.cz>,
	Andrew Morton <akpm@...ux-foundation.org>,
	lkml <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] console keyboard mapping broken by 04c71976

On Wed, Jun 11, 2008 at 03:03:04PM +0100, Samuel Thibault wrote:
> Err, at quick look it looks to me rather like a bug kbd, which doesn't
> cope with the console being in unicode mode.  Which distribution are you
> using?
> 
> In unicode mode, k_self is really meant to hold unicode values (there is
> no other way to provide an arbitrary unicode value in keyboard maps),
> and thus kbd should translate KT_LETTER's value from the map file's
> encoding (set by the charset directive) to unicode.

I am actually hunting down a bug this causes in openSUSE. We use
kbd-1.12. kbd does not translate anything to unicode - there is
no space for that in the 8 bits the keycode uses for the value.
The kernel needs to take care for the conversion.

I'll demonstrate the problem on tracing kbd_keycode() in
drivers/char/keyboard.c when the key "2" (keycode 3) is pressed.
The expected result is the letter letter "e" with a caron [CARON]
accent, code 0xec in iso-8859-2 [88592].

The keysym for this key in the Czech keyboard is set to 0xbec
by a call to KDSKBENT, which stores it as 0xfbec in the map.

	...
	type = KTYP(keysym);		// 0xfb
	...
	type -= 0xf0;			// 0xb
        if (type == KT_LETTER) {	// true
                type = KT_LATIN;	// 0

	...
        (*k_handler[type])(vc, keysym & 0xff, !down); 
		// calls k_self, note there is really no space for a 
		// full unicode representation ;-)

So, we need to perform the conversion in k_self (or later).  Your
patch removed it from k_unicode, but only does it in k_self when
the keyboard mode is not VC_UNICODE.

[CARON]: http://en.wikipedia.org/wiki/Caron
[88592]: http://en.wikipedia.org/wiki/Iso-8859-2

Regards,

-- 
Jiri Bohac <jbohac@...e.cz>
SUSE Labs, SUSE CZ

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